My city is twinned with Rotterdam, which is a decent surface-level comparison but lacking something. Until someone with intimate knowledge of the region proves me spectacularly wrong I'll cling to my conjecture that Baltimore is the Belfast of America.
My city is (sort of, not really) twinned with Vallejo, California, which makes quite some sense (important navy base, blander than the surroundings, relatively similar climates, they are also of similar sizes though this was not the case historically), but I'm sure better candidates for the La Spezia of America exist. I have no specific answer however.
